It is known to provide such a sealing device with means for combined draining of the oil accumulated by the scraper ring and of gas leaking through said scraper ring. In many cases it will be desirable to pump the leaked gas back to the high pressure chamber after it has been separated from its oil contents. This arrangement has the drawback that the oil separator needs service at intervals, and consequently one object of the present invention is to provide a sealing device in which no separation of oil and gas will be necessary.